1. Field of the Invention
This invention relates to lamination pouches for paper sheets, cards, or the like.
2. Description of the Prior Art
Heavy gauge laminating pouches consisting of paired five, ten and even fourteen mil polyester sheets bearing polyethylene or copolymer heat reactivatible adhesives are commonly used as described in U.S. Pat. No. 3,711,355. These pouches find extensive use in the so-called identification card market. Such cards are shown in U.S. Pat. No. 3,279,826. Identification cards generally are wallet size and comparatively rigid. While small, heavy gauge pouches are useful in the fabrication of identification cards, large heavy gauge pouches, despite their convenience, are not economical for laminating typical sheet documents such as standard 81/2 by 11 inch paper sheets. Attempts to market larger, more economical pouches employing pairs of 11/2 or 3 mil laminating film sheets (including the heat reactivatible adhesive layer) have the disadvantage of being too flimsy and consequently difficulty is encountered in inserting the product to be laminated within the pouch. Leaves of the pouch become electrostatically charged and are difficult to separate and straighten when the films are very thin. Furthermore, the flimsy or limp unlaminated pouch together with the product cannot consistently be processed successfully through oven-type laminators as described in U.S. Pat. No. 3,711,355 without a carrying device. Previously, a carrying device formed of a separate, folded sheet of aluminum foil or aluminum clad paper was provided to loosely receive a product to be laminated with polyester films loosely positioned on either side of the product being laminated. This carrier was intended to receive excessive heat reactivatible adhesive squeezeout when laminating with relatively thick film laminates.
As a result of these difficulties, thin film laminates have generally been fabricated in roll film laminators as shown, for instance, in U.S. Pat. No. 3,401,439 where a continuous web of film containing the product to be laminated issues from the machine and individually laminated sheets are severed from the web and trimmed appropriately. While this laminating process is effective, the web severance and trimming aspects are time-consuming and difficult to do well.